UE-to-network relay initiation and configuration

ABSTRACT

Technology for a relay user equipment (UE) operable to act as a relay between a remote UE and an eNodeB is disclosed. The relay UE can receive, from the eNodeB, a relay configuration message that includes one or more relay configuration parameters. The relay UE can identify relay UE information associated with one or more relay parameters of the relay UE. The relay UE can determine to act as the relay for the remote UE based on the one or more relay configuration parameters and the relay UE information. The relay UE can transmit a discovery message to the remote UE in order to establish a direct connection between the relay UE and the remote UE, wherein the relay UE is configured to relay data from the eNodeB to the remote UE via the direct connection between the relay UE and the remote UE.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/566,650 filed Oct. 13, 2017 which is a 371 Nationalizationof PCT Application No. PCT/US2015/064833 filed Dec. 9, 2015 which claimspriority to U.S. Provisional Patent Application No. 62/161,761, filedMay 14, 2015 the entire specification of which is hereby incorporated byreference in its entirety for all purposes.

BACKGROUND

Wireless mobile communication technology uses various standards andprotocols to transmit data between a node (e.g., a transmission station)and a wireless device (e.g., a mobile device). Some wireless devicescommunicate using orthogonal frequency-division multiple access (OFDMA)in a downlink (DL) transmission and single carrier frequency divisionmultiple access (SC-FDMA) in an uplink (UL) transmission. Standards andprotocols that use orthogonal frequency-division multiplexing (OFDM) forsignal transmission include the third generation partnership project(3GPP) long term evolution (LTE), the Institute of Electrical andElectronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m),which is commonly known to industry groups as WiMAX (Worldwideinteroperability for Microwave Access), and the IEEE 802.11 standard,which is commonly known to industry groups as WiFi.

In 3GPP radio access network (RAN) LTE systems, the node can be acombination of Evolved Universal Terrestrial Radio Access Network(E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhancedNode Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), whichcommunicates with the wireless device, known as a user equipment (UE).The downlink (DL) transmission can be a communication from the node(e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL)transmission can be a communication from the wireless device to thenode.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the disclosure will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the disclosure; and, wherein:

FIG. 1 illustrates a device-to-device (D2D) discovery and communicationarchitecture in accordance with an example;

FIG. 2 illustrates a relay user equipment (UE) acting as a relay betweena remote UE and an eNodeB in accordance with an example;

FIG. 3 is abstract syntax notation (ASN) code describing a systeminformation block (SIB) in accordance with an example;

FIG. 4 illustrates signaling that enables a relay user equipment (UE) toact as a relay between an eNodeB and a remote UE in accordance with anexample;

FIG. 5 illustrates signaling that enables a relay user equipment (UE) toact as a relay between an eNodeB and a remote UE in accordance with anexample;

FIG. 6 illustrates signaling that enables a relay user equipment (UE) toact as a relay between an eNodeB and a remote UE in accordance with anexample;

FIG. 7 illustrates signaling that enables a relay user equipment (UE) toact as a relay between an eNodeB and a remote UE in accordance with anexample;

FIG. 8 illustrates signaling that enables a relay user equipment (UE) toact as a relay between an eNodeB and a remote UE in accordance with anexample;

FIG. 9 illustrates signaling that enables a relay user equipment (UE) toact as a relay between an eNodeB and a remote UE in accordance with anexample;

FIG. 10 is abstract syntax notation (ASN) code describing a sidelinkuser equipment (UE) information message in accordance with an example;

FIG. 11 is abstract syntax notation (ASN) code describing a sidelinkuser equipment (UE) relay interest indication message in accordance withan example;

FIG. 12 is abstract syntax notation (ASN) code describing a radioresource control (RRC) connection reconfiguration message in accordancewith an example;

FIG. 13 illustrates signaling that enables a relay user equipment (UE)to act as a relay between an eNodeB and a remote UE in accordance withan example;

FIG. 14 illustrates signaling that enables a relay user equipment (UE)to act as a relay between an eNodeB and a remote UE in accordance withan example;

FIG. 15 is abstract syntax notation (ASN) code describing a sidelinkdiscovery configuration information element (IE) in accordance with anexample;

FIG. 16 is abstract syntax notation (ASN) code describing a sidelinkdiscovery configuration information element (IE) in accordance with anexample;

FIG. 17 illustrates relay reselection signaling in accordance with anexample;

FIG. 18 illustrates relay reselection signaling in accordance with anexample;

FIG. 19 depicts functionality of a relay user equipment (UE) operable toact as a relay between a remote UE and an eNodeB in accordance with anexample;

FIG. 20 depicts functionality of a relay user equipment (UE) operable toact as a relay between a remote UE and an eNodeB in accordance with anexample;

FIG. 21 depicts functionality of an eNodeB operable to instruct a relayuser equipment (UE) to act as a relay between the eNodeB and a remote UEin accordance with an example;

FIG. 22 depicts functionality of a remote user equipment (UE) operableto communicate with an eNodeB via a relay UE in accordance with anexample;

FIG. 23 illustrates a diagram of a wireless device (e.g., UE) inaccordance with an example; and

FIG. 24 illustrates a diagram of a wireless device (e.g., UE) inaccordance with an example.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of thetechnology is thereby intended.

DETAILED DESCRIPTION

Before the present technology is disclosed and described, it is to beunderstood that this technology is not limited to the particularstructures, process actions, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular examples only and is not intended to be limiting. The samereference numerals in different drawings represent the same element.Numbers provided in flow charts and processes are provided for clarityin illustrating actions and operations and do not necessarily indicate aparticular order or sequence.

EXAMPLE EMBODIMENTS

An initial overview of technology embodiments is provided below and thenspecific technology embodiments are described in further detail later.This initial summary is intended to aid readers in understanding thetechnology more quickly but is not intended to identify key features oressential features of the technology nor is it intended to limit thescope of the claimed subject matter.

Device to device (D2D) communication for Evolved Universal TerrestrialRadio Access (E-UTRA) or Long Term Evolution (LTE) is being standardizedas of 3GPP LTE Release 12. D2D feature enables the direct communicationof data between user equipments (UEs) over the cellular radio spectrum,but without the data being carried by the cellular networkinfrastructure. Within 3GPP, the D2D communication feature can bereferred to as ProSe (Proximity Services) Direct Communication. InRelease 12 and 13, D2D is primarily targeted for public safety usecases. Therefore, public safety workers can communicate with each otherusing radio frequency (RF) communications when there is no LTEconnection available. In this use case, there is no reliance on networkcoverage. However, for future releases, commercial applications of D2Dare also considered.

In Release 12, there are several D2D features that are covered, such asProSe device to device discovery in network coverage. ProSe discoveryrefers to the process by which one UE detects and identifies another UEin proximity using E-UTRAN radio signals. Other D2D features includeProSe device to device broadcast communication, and higher layer (e.g.,access stratum (AS) layer) support to enable groupcast (e.g., broadcastor multicast) and unicast over a physical layer broadcast communication.

FIG. 1 illustrates an exemplary device-to-device (D2D) discovery andcommunication architecture. More specifically, FIG. 1 illustrates aD2D/ProSe non-roaming reference architecture. A first UE 102 can beconnected to a E-UTRAN 110 over a first LTE-Uu interface, and a secondUE 106 can be connected to the E-UTRAN 110 over a second LTE-Uuinterface. The first UE 102 can execute a first ProSe application 104and the second UE 106 can execute a second ProSe application 108. Thefirst UE 102 and the second UE 106 can be connected via a PC5 interface.In other words, the PC5 interface is the communication link between thetwo ProSe enabled UEs 102, 106 in direct communication.

In one example, the E-UTRAN 110 can be connected to an Evolved PacketCore (EPC) 112 via an S1 interface. The EPC 112 can be connected to aProSe function 114 via a PC4 interface, and the EPC 112 can be connectedto a ProSe application server 116 over an SGi interface. The ProSefunction 114 and the ProSe application server 116 can be connected via aPC2 interface. In addition, one of the UEs can be connected to the ProSefunction 114 and the ProSe application server 116. For example, thesecond UE 106 can be connected to the ProSe function 114 over a PC3interface, and the second ProSe application 108 that executes on thesecond UE 106 can be connected to the ProSe application server 116 via aPC1 interface.

Release 13 aims to introduce enhancements to LTE D2D communications anddiscovery meeting requirements for public safety for: (1) in-networkcoverage (intra-cell and inter-cell), (2) partial network coverage, and(3) outside network coverage scenarios. For non-public safety discovery,the enhancements to LTE D2D communications can be for in-networkcoverage (intra-cell and inter-cell).

In addition, Release 13 aims to support the extension of networkcoverage using layer 3 (L3)-based ProSe UE-to-Network Relays. A ProSeUE-to-Network relay can also be referred to as a relay UE. The relay UEcan perform a ProSe UE-to-Network Relay function, which supports therelay of unicast traffic to remote UEs that are not served by theE-UTRAN and the network. In other words, the relay UE can act as a relaybetween the network and the remote UE that is out-of-coverage. The relayUE will be in-coverage with the network in order to forward the data tothe out-of-coverage remote UE. The relay UE can relay unicast traffic inboth uplink (UL) and downlink (DL). In other words, the relay UE canforward information from the remote UE in uplink to the network, as wellas forward information from the network in downlink to the remote UE.The relay UE can enhance coverage to UEs that are outside the network.The relay UE can provide a generic L3 forwarding function that can relayInternet Protocol (IP) traffic that is relevant for public safetycommunication. In addition, the relay UE can relay IP traffic (e.g.,voice data, video data) to support service continuity for the remote UE.

In one example, the network (e.g., an eNodeB) can control the initiationof the ProSe UE-to-Network Relay feature. The eNodeB can control theinitiation of the ProSe UE-to-Network Relay feature per cell or perrelay UE or both. The relay UE can be initiated or configured to act asa relay while a connection is established between the relay UE and thenetwork. A given UE (i.e., the remote UE) can (re)select the relay UE,and then a connection can be established between the remote UE and therelay UE. At this point, the relay UE can forward data from the networkto the remote UE, or vice versa.

As described in greater detail below, the relay UE can be initiatedand/or configured to act as a relay via a generic network configurationin a system information block (SIB). The relay UE can determine to actas a relay based on a relay configuration message received from thenetwork, or alternatively, the network can instruct the relay UE to actas a relay using the relay configuration message. In other words, agiven UE can determine to act as a relay UE, or can be instructed to actas a relay UE. As described in greater detail below, the remote UE canmove from in-coverage to out of coverage. In other words, the remote UEcan initially be connected to the network, but after the remote UE movesout of coverage, the remote UE can connect to a relay UE and communicatewith the network via the relay UE. The actions performed by the remoteUE after moving out of coverage can be initiated by the remote UE, or bythe relay UE or the eNodeB. As described in greater detail below, therelay UE can initiate a relay discovery and selection procedure in orderto connect with the remote UE. In one example, the relay UE can act as arelay only when its network connection channel quality is above adefined threshold, and the remote UE can only perform a relay selectionprocedure when its network connection channel quality is below a definedthreshold.

FIG. 2 illustrates an example of a relay user equipment (UE) 204 actingas a relay between a remote UE 202 and an eNodeB 206. The eNodeB 206 caninclude processor(s) 207 and memory 209. The relay UE 204 can also bereferred to as a ProSe UE-to-Network Relay. The relay UE 204 can beconnected to the eNodeB 206 via a Uu interface. Therefore, the relay UE204 can be in-coverage with respect to the network. The remote UE 202can be out-of-coverage. The remote UE 202 may not be directly connectedto the eNodeB 206, but rather is directly connected to the relay UE 204via a PC5 interface. The relay UE 204 can act as an intermediary betweenthe remote UE 202 that is out-of-coverage and the eNodeB 206. The eNodeB206 can be part of an Evolved Packet Core (EPC) 208, and the eNodeB 206can be connected to a public safety application server (AS) 210 via anSGi interface.

In one example, the relay UE 204 can be configured for relaying by theeNodeB 206. The configured relay operation can include both discoveryand one-to-one communication between the relay UE 204 and the remote UE202, or the configured relay operation can include only one-to-onecommunication if the Access Stratum (AS) layer cannot distinguish if thediscovery message is delivered for the ProSe UE-to-Network Relayprocedure or for another type of procedure (e.g., group memberdiscovery). In one example, the configurations below can be sent via theAccess Stratum (AS) layer because if the eNodeB 206 is to have tightcontrol over these procedures, the eNodeB 206 can be aware that a givenUE is initiating a UE-to-Network Relay discovery in advance of themessage.

In one configuration, as part of initiating the UE-to-Network relayoperation, the eNodeB 206 can broadcast a generic network configurationmessage to a plurality of UEs. In particular, the eNodeB 206 canbroadcast a relay configuration information message that containscertain cell specific information. The relay configuration informationmessage can be part of a novel system information block (SIB) that isbroadcast from the eNodeB 206 to the plurality of UEs, or the relayconfiguration information message can be part of an existing SIB that isbroadcast from the eNodeB 206 to the plurality of UEs. In one example,the relay configuration information message can include various genericrelay-related cell-wide configuration parameters (or relay configurationparameters), such as an s-relay parameter (threshold relay lower), athreshold relay upper parameter, a relay mobility configurationparameter, an initiate relay from idle parameter, and a relay operationsupported parameter.

In one example, the s-relay parameter (threshold relay lower) canrepresent a Uu link quality threshold above which a given UE can act asa relay. In other words, the given UE can have a link quality of acertain level in order to support acting as a relay for the remote UE202. The Uu link quality threshold can be a Reference Signal ReceivedPower (RSRP) and/or a Reference Signal Received Quality (RSRQ)threshold. The s-relay parameter (threshold relay lower) can be used toensure that UEs in poor coverage situations do not become relays,thereby avoiding excess use of the cell's resources to carry the relayedtraffic between the eNodeB 206 and the relay UE 204. In one example, thes-relay parameter can be defined as thresholdLowRelayUE ordiscoveryThresholdLowRelayUE or in a similar manner. The s-relayparameter can be a lower threshold above which a particular UE can actas a relay, and the threshold upper parameter is a parameter below whicha particular UE can act as a relay and above which the particular UEcannot act as a relay. In other words, both the s-relay parameter andthe threshold upper parameter provide a range within which a particularUE can act as a relay.

In one example, the threshold relay upper parameter can represent anupper threshold of Uu link quality above which a given UE cannot act asa relay. The threshold relay upper parameter can be used to prevent UEslocated in proximity to the cell center from becoming relays. UEslocated in proximity to the cell center are unlikely to be useful forthe purpose of relaying traffic from remote UEs that are out ofcoverage, and therefore, the resource usage and interference associatedwith discovery announcements can be avoided.

In one example, the relay mobility configuration parameter can representan acceptable mobility state for a given UE to act as a relay. Forexample, if the relay mobility configuration parameter is set to “low,”then this indicates that the given UE can be a low mobility UE in orderto act as a relay.

In one example, the initiate relay from idle parameter can be set to“ON” or “OFF.” When set to “ON,” the UE may initiate relay operationwhile being in idle mode, and conversely, when set to “OFF,” the UE maynot initiate relay operation while being in idle mode. In other words,when set to “OFF,” the UE should go to the connected mode to initiaterelay operation. Alternatively, instead of the initiate relay from idleparameter, if there is no relay configuration information and the eNodeB206 supports relay operation, a given UE can implicitly assume to go tothe connected mode to enable relay operation.

In one example, the relay operation supported parameter can representwhether the cell supports relay operation. For example, the relayoperation supported parameter can be set to “YES” when the cell supportsrelay operation, and conversely, the relay operation supported parametercan be set to “NO” when the cell does not support relay operation. Thepresence of relay related parameters can also be an indication that therelay operation is supported in the cell.

As described in further detail below, the eNodeB 206 can broadcast therelay configuration information message with the relay configurationparameters to the relay UE 204. The relay configuration parameters caninclude the s-relay parameter (threshold relay lower), the thresholdrelay upper parameter, the relay mobility configuration parameter, theinitiate relay from idle parameter, and the relay operation supportedparameter. Based on the relay configuration parameters included in therelay configuration information message, the relay UE 204 can decide toact as a relay. Alternatively, after the relay UE 204 receives the relayconfiguration parameters included in the relay configuration informationmessage can instruct the relay UE 204 to act as a relay. In other words,in a first scenario, the relay UE 204 decides to act as a relay, and ina second scenario, the eNodeB 206 decides for the relay UE 204 to act asa relay.

FIG. 3 is exemplary abstract syntax notation (ASN) code describing anovel system information block (SIB). The SIB can be broadcast from aneNodeB to a relay UE. The SIB can include a relay operation supportedparameter. In addition, the SIB can include a relay configurationinformation message that contains a number of relay configurationparameters. The relay configuration parameters can include an s-relayparameter (threshold relay lower), a threshold relay upper parameter, arelay mobility configuration parameter, and an initiate relay from idleparameter.

FIG. 4 illustrates exemplary relay initiation signaling that enables arelay user equipment (UE) 420 to act as a relay between an eNodeB 430and a remote UE 410. The eNodeB 430 can broadcast a relay configurationinformation message to the relay UE 420. The relay configurationinformation message can be included in a system information block (SIB)18, a SIB 19 or another SIB. The relay configuration information messagecan include various relay configuration parameters, such as an s-relayparameter (threshold relay lower), a threshold relay upper parameter, arelay mobility configuration parameter, and an initiate relay from idleparameter.

Based on the relay configuration parameters included in the relayconfiguration information message (and UE internal information), therelay UE 420 can determine whether or not to initiate the relayfunctionality. After the relay UE 420 determines to act as a relay, therelay UE 420 can transmit a discovery message to the remote UE 410. Thediscovery message can announce or advertise that the relay UE 420 isacting as a relay, and that the relay UE 420 is ready to receive adirect communication request from the remote UE 410. After transmissionof the discovery message from the relay UE 420 to the remote UE 410,one-to-one communication can take place between the relay UE 420 and theremote UE 410. For example, the remote UE 410 can communicate the directcommunication request message to the relay UE 420, and the remote UE 410and the relay UE 420 can perform a mutual authentication procedure.

As shown in FIG. 4, other than the setting of the broadcastconfiguration parameters, the eNodeB 430 has no involvement in the relayUE's decision on whether to become a relay. In other words, the relay UE420 is autonomous in making the decision on whether or not to act as arelay based on the relay configuration parameters.

In one example, the relay UE 420 can determine whether to act as a relaybased on the UE internal information. The UE internal information caninclude measurements (e.g., RSRP and/or RSRQ measurements) of theserving cell to compare with thresholds that are provided as part of therelay configuration parameters. In other words, the relay UE 420 cancompare its own measurements with the thresholds included in the s-relayparameter (threshold relay lower) and the threshold relay upperparameter, and based on this comparison, the relay UE 420 can determinewhether or not to act as a relay. In one example, the UE internalinformation can include battery status information. For example, therelay UE 420 may only decide to act as a relay if the relay UE's batterystatus is above a certain threshold, or if the relay UE 420 is connectedto a permanent power supply. In one example, the UE internal informationcan include user input information. For example, the relay UE 420 mayonly decide to act as a relay if a user/upper layer configures a settingon the relay UE 420 to enable the relay functionality. Therefore, therelay UE 420 can use the UE internal information in combination with therelay configuration parameters when determining whether or not to act asa relay.

FIG. 5 illustrates exemplary relay initiation signaling that enables arelay user equipment (UE) 520 to act as a relay between an eNodeB 530and a remote UE 510. The eNodeB 530 can broadcast a system informationblock (SIB) 18 or a SIB 19 to the relay UE 520. In this configuration,the SIB 18 or SIB 19 may or may not include a relay configurationinformation message with relay configuration parameters. After the relayUE 520 receives the SIB 18 or SIB 19 from the eNodeB 530, the relay UE520 communicates a discovery message to the remote UE 510. At thispoint, the relay UE 520 sends the discovery message merely to initiatedevice-to-device (D2D) communications with the remote UE 510, and not toact as a relay for the remote UE 510. After transmission of thediscovery message from the relay UE 520 to the remote UE 510, one-to-onecommunication can take place between the relay UE 520 and the remote UE510. For example, the remote UE 510 can communicate a directcommunication request message to the relay UE 520.

If the relay configuration is not broadcast in SIB18/19, at this point,the eNodeB 530 can separately broadcast a relay configuration messagewith relay configuration parameters to the relay UE 520. Based on therelay configuration parameters and UE internal information, the relay UE520 can determine whether or not to act as a relay for the remote UE510. In addition, the remote UE 510 and the relay UE 520 can perform amutual authentication procedure. After the mutual authenticationprocedure, the relay UE 520 can either be acting as a relay for theremote UE 510, or the relay UE 520 may simply perform D2D communicationswith the remote UE 510 without acting as a relay.

One difference between FIG. 4 and FIG. 5 is when the relay UE determinesto act as a relay. In FIG. 4, the relay UE decides to act as a relaybefore sending the discovery message to the remote UE. For this option,the AS layer can reject the request from the upper layer if thediscovery message is for the relay UE, but the relay UE cannot performrelay operation according to the eNodeB's broadcast configuration. InFIG. 5, the relay UE can determine to act as a relay after the discoverymessage is sent to the remote UE. In FIG. 5, the AS layer can reject therequest from the upper layer if one-to-one communication is enabled. Inone example, the signaling shown in FIG. 4 can be more beneficial fromthe UE perspective, as it can avoid announcing/monitoring discoverymessage from UEs that cannot perform the UE-to-NW relay operation.

FIG. 6 illustrates exemplary relay initiation signaling that enables arelay user equipment (UE) 620 to act as a relay between an eNodeB 630and a remote UE 610. The eNodeB 630 can broadcast a relay configurationinformation message to the relay UE 620. The relay configurationinformation message can be included in a system information block (SIB)18, a SIB 19 or another SIB. The relay configuration information messagecan include various relay configuration parameters, such as an s-relay(threshold relay lower) parameter, a threshold relay upper parameter, arelay mobility configuration parameter, and an initiate relay from idleparameter.

Based on the relay configuration parameters and UE internal information,the relay UE 620 can determine to act as a relay for the remote UE. Therelay UE 620 can communicate a sidelink UE information message to theeNodeB 630, wherein the sidelink UE information message indicates therelay UE's intent to act as a relay for the remote UE 610. In thisconfiguration, the relay UE 620 makes the decision on whether to act asa relay as opposed to the eNodeB 630.

After the relay UE 620 determines to act as a relay, the relay UE 620can transmit a discovery message to the remote UE 610. The discoverymessage can announce that the relay UE 620 is acting as a relay, andthat the relay UE 620 is ready to receive a direct communication requestfrom the remote UE 610. After transmission of the discovery message fromthe relay UE 620 to the remote UE 610, one-to-one communication can takeplace between the relay UE 620 and the remote UE 610. For example, theremote UE 610 can communicate the direct communication request messageto the relay UE 620, and the remote UE 610 and the relay UE 620 canperform a mutual authentication procedure.

FIG. 7 illustrates exemplary relay initiation signaling that enables arelay user equipment (UE) 720 to act as a relay between an eNodeB 730and a remote UE 710. The eNodeB 730 can broadcast a relay configurationinformation message to the relay UE 720. The relay configurationinformation message can be included in a system information block (SIB)18, a SIB 19 or another SIB. The relay configuration information messagecan include various relay configuration parameters, such as an s-relayparameter (threshold relay lower) a threshold relay upper parameter, arelay mobility configuration parameter, and an initiate relay from idleparameter.

The relay UE 720 can determine whether or not it is interested to act asa relay based on the relay configuration parameters and UE internalinformation. The relay UE 720 can communicate a sidelink UE informationmessage to the eNodeB 730, wherein the sidelink UE information messageindicates whether or not the relay UE 720 is interested in acting as arelay. In this configuration, the relay UE 720 does not make thedecision on whether or not to act as a relay. Rather, the eNodeB 730receives the sidelink UE information message with the relay UE'sinterest in acting as a relay, and then the eNodeB 730 makes a finaldetermination on whether the relay UE 720 should enable its relayfunctionality. If the eNodeB 730 determines that the relay UE 720 is toact as a relay, the eNodeB 730 can communicate a relay initiation andconfiguration message to the relay UE 720. The relay initiation andconfiguration message can be dedicated signaling that is specific to therelay UE 720 (i.e., not broadcast). In some cases, the eNodeB 730 canmerely send an acknowledgement (ACK) to the relay UE 720 indicating thatthe relay UE 720 is permitted to act as a relay.

After reception of the relay initiation and configuration message (or anACK), the relay UE 720 can communicate a discovery message to the remoteUE 710. The discovery message can announce that the relay UE 720 isacting as a relay, and that the relay UE 720 is ready to receive directcommunication requests from remote UEs. The remote UE 710 cancommunicate a direct communication request to the relay UE 720, and thenthe remote UE 710 and the relay UE 720 can perform a mutualauthentication procedure.

In this configuration, (i.e., when the eNodeB determines for the relayUE to act as a relay), an increased amount of signaling overhead mayoccur. However, such an approach enables the eNodeB to have greatercontrol over which UEs become relays. For example, the eNodeB may wantto limit the number of UEs that become relays in order to reduce theoverhead associated with discovery message transmissions from the relayUEs.

FIG. 8 illustrates exemplary relay initiation signaling that enables arelay user equipment (UE) 820 to act as a relay between an eNodeB 830and a remote UE 810. The eNodeB 830 can broadcast a relay configurationinformation message to the relay UE 820. The relay configurationinformation message can be included in a system information block (SIB)18, a SIB 19 or another SIB. The relay configuration information messagecan include various relay configuration parameters. At this point, therelay UE 820 may not be acting as a relay. The relay UE 820 can transmita discovery message to the remote UE 810. The discovery message may beto initiate D2D communication between the relay UE 820 and the remote UE810. The remote UE 810 can transmit a direct communication request tothe relay UE 820.

After the discovery message and the direct communication request arecommunicated, the relay UE 820 can transmit a sidelink UE informationmessage to the eNodeB 830, wherein the sidelink UE information messageindicates that the relay UE 820 is interested in acting as a relay. TheeNodeB 830 can determine whether or not the relay UE 820 is to act as arelay, and if so, the eNodeB 830 can communicate a relay initiation andconfiguration message to the relay UE 820. The relay initiation andconfiguration message can be dedicated signaling that is specific to therelay UE 820 (i.e., not broadcast). In addition, the remote UE 810 andthe relay UE 820 can perform a mutual authentication procedure. At thispoint, the relay UE 820 can be configured to act as a relay for theremote UE 810.

In this configuration, the relay UE 820 may have to obtain eNodeBauthorization for each UE-to-Network relay connection, or when relayoperation is actually initiated upon the direct communication requestmessage rather than the discovery message.

FIG. 9 illustrates exemplary relay initiation signaling that enables arelay user equipment (UE) 920 to act as a relay between an eNodeB 930and a remote UE 910. The remote UE 910 can initially be in-coverage ofthe eNodeB 930. In other words, at least initially, a connection can beestablished between the remote UE 910 and the eNodeB 930. The eNodeB 930can broadcast a relay configuration information message to the relay UE920. The relay configuration information message can be included in asystem information block (SIB) 18, a SIB 19 or another SIB. The relayconfiguration information message can include various relayconfiguration parameters. At this point, the relay UE 920 may not beacting as a relay. The relay UE 920 can transmit a discovery message tothe remote UE 910. The discovery message may be to initiate D2Dcommunication between the relay UE 920 and the remote UE 910.

In one example, the remote UE 910 can send a measurement report to theeNodeB 930 via the connection that is established between the remote UE.Based on the measurement report, the eNodeB 930 can transmit a relayinitiation and configuration message to the relay UE 920, whichinstructs the relay UE 920 to act as a relay for the remote UE 910. Inother words, the eNodeB 930 may determine that the connection betweenthe remote UE 910 and the eNodeB 930 is below a defined threshold basedon the remote UE's measurement report. Therefore, the eNodeB 930 caninstruct the relay UE 920 to act as a relay via the relay initiation andconfiguration message, which can be dedicated signaling that is specificto the relay UE 920 (i.e., not broadcast). Since the relay UE 920 hasalready received the relay configuration information message with therelay configuration parameters, the relay UE 920 can begin acting as arelay for the remote UE 910 after receiving the relay initiation andconfiguration message from the eNodeB 930.

In one example, the eNodeB 930 can communicate a relay informationmessage to the remote UE 910. The relay information message may indicatethat the relay UE 920 is to act as a relay for the remote UE 910. Theremote UE 910 can send a direct communication request to the relay UE920. After a mutual authentication procedure is performed between theremote UE 910 and the relay UE 920, the relay UE 920 can act as a relaybetween the remote UE 910 and the eNodeB 930. At this point, the remoteUE 910 may still be within coverage (albeit at a poor connection withthe eNodeB 930), or the remote UE 910 can be out-of-coverage.

In one configuration, relay initiation can be dynamically performed at agiven UE (e.g., the relay UE). The relay UE can determine whether to actas a relay based on relay configuration parameters received from theeNodeB, as well as UE internal information. For example, if the relay UEdetermines that it satisfies various thresholds included in the relayconfiguration parameters, the relay UE can send dedicated signaling tothe eNodeB to indicate that the relay UE is interested in acting like arelay. In other words, the relay UE can indicate an interest to act likea relay and request the eNodeB for permission to act as the relay. Atrigger for the relay UE to send a new message or use an existingmessage to piggyback this request to act like a relay may be a relayconfigured by upper layers (e.g., upon initiation from an application).However, in this case, even though the relay UE initiates the relayoperation, the eNodeB still makes a final determination on whether therelay UE is permitted to act as a relay.

FIG. 10 is exemplary abstract syntax notation (ASN) code describing asidelink user equipment (UE) information message. The sidelink UEinformation message can be communicated from a relay UE to an eNodeB.The sidelink UE information message can include a relay interestparameter, which indicates whether or not the relay UE is interested inacting as a relay.

In one example, the sidelink UE information message can be an existingmessage that is used to communicate D2D-related UE specific information,and the sidelink UE information message may be re-utilized for thepurpose of a UE-initiated relay operations. A given UE can send thesidelink UE information message to the eNodeB, wherein the sidelink UEinformation message includes a relay interest field. The relay interestfield enables the given UE to indicate to the eNodeB an interest to actas a relay UE (i.e., to enable its relay functionality). For example,the given UE may include relay interest field if the UE's conditions forbecoming a relay are met (e.g., based on the relay configurationparameters contained in a system information and UE internalinformation).

FIG. 11 is exemplary abstract syntax notation (ASN) code describing asidelink user equipment (UE) relay interest indication message. Thesidelink UE relay interest indication message can be communicated from arelay UE to an eNodeB. The sidelink UE relay interest indication messagecan include a relay interest parameter, which indicates whether or notthe relay UE is interested in acting as a relay.

In one example, the sidelink UE relay interest indication message, whichis specific to D2D, can be utilized for the purpose of UE-initiatedrelay operations. The sidelink UE relay interest indication message canbe a new message that is added to 3GPP LTE Technical Specification (TS)36.331. A given UE can send the sidelink UE relay interest indicationmessage to the eNodeB, wherein the sidelink UE relay interest indicationmessage includes the UE's relay interest indication to the eNodeB. Thesidelink UE relay interest indication message can be provided to theeNodeB at any point during which the UE is in RRC connected mode.

In one example, the sidelink UE information message and the sidelink UErelay interest indication message can be similar to the sidelink UEinformation message communicated from the relay UE to the eNodeB, asdescribed above with respect to FIGS. 7 and 8.

As described in further detail below, after the eNodeB receives thesidelink UE information message or the sidelink UE relay interestindication message from the relay UE, the eNodeB can respond with theappropriate relay configuration parameters. In other words, the UE relayinitiation (in which a given UE indicates relay operation interest) canbe followed by a UE-specific relay configuration, which is communicatedfrom the eNodeB to the relay UE. The UE-specific relay configuration canbe similar to the relay initiation and configuration messagecommunicated from the eNodeB to the relay UE, as described above withrespect to 7-9. In addition, the communication of the sidelink UEinformation message can allow for adjustment of any radio resourcemanagement (RRM) parameters at the eNodeB (e.g., the eNodeB may considermoving the relay UE to a different frequency).

In one configuration, based on the sidelink UE information messagereceived from the relay UE, the eNodeB can initiate the UE's relayoperation and provide UE-specific relay configuration information to therelay UE. The UE-specific relay configuration information can also bereferred to as a relay initiation and configuration message.

In other scenarios, the eNodeB can communicate the relay initiation andconfiguration message to the relay UE in response to the remote UE'srequest for a relay UE, or in response to a remote UE's measurementreport, as described earlier. In these scenarios, the relay UE may notsend the sidelink UE information message to the eNodeB (which indicatesan interest to act as a relay). Rather, without any signaling from agiven UE, the eNodeB may transmit the relay initiation and configurationmessage to the given UE, and the given UE may begin acting as a relayfor the remote UE.

In one example, the relay initiation and configuration message can becommunicated from the eNodeB to the relay UE along with existing RRCmessaging. For example, the relay initiation and configuration messagecan be part of an RRC connection reconfiguration message sent from theeNodeB to the relay UE. Alternatively, the relay initiation andconfiguration message can be a new message that is communicated from theeNodeB to the relay UE.

FIG. 12 is exemplary abstract syntax notation (ASN) code describing aradio resource control (RRC) connection reconfiguration message. The RRCconnection reconfiguration message can be communicated from an eNodeB toa relay UE, and used to initiate the UE's relay operation. When theeNodeB initiates the UE's relay operation in an existing RRC connectionreconfiguration message, the RRC connection reconfiguration message caninclude a sidelink relay configuration field. The sidelink relayconfiguration field can include various parameters, such as a sidelinkrelay discovery start (SLrelayDiscoveryStart) parameter, a relaydiscovery periodicity (t_relayDiscoveryPeriodicity) parameter, a relayoperation timer (t_relayOperationTimer) parameter, a sidelink maximumremote UE (SLmaxRemoteUEs) parameter, a sidelink relay resourceconfiguration (SLrelayResourceConfiguration) parameter, a sidelinkremote UE authorization (SLremoteUEAuthorization) parameter, and asidelink relay control configuration (SLrelayControlConfiguration)parameter. Based on the reception of these parameters, the relay UE canbe configured to act as a relay for a remote UE.

In one example, the sidelink relay discovery start(SLrelayDiscoveryStart) parameter can configure the UE to act as a relay(i.e., to enable its relay functionality). For example, the sidelinkrelay discovery start parameter can be set to “ON.” In response toreceiving the sidelink relay discovery start parameter, the relay UE caninitiate the transmission of discovery announcement messages to remoteUEs for relaying purposes.

In one example, the relay discovery periodicity(t_relayDiscoveryPeriodicity) parameter can indicate a frequency ofrelay discovery operation (e.g., a configurable timer). This parametercan indicate a periodicity of an announce procedure by the relay UE,wherein the relay UE performs the announce procedure to advertise itselfas acting as a relay. In one example, even if the periodicity of thediscovery message is defined in the upper layer, the access stratum (AS)layer can perform a retransmission of the relay discovery periodicity,e.g., in order to increase the reliability of the discovery message.

In one example, the relay operation timer (t_relayOperationTimer)parameter can include a timer indicating how long the relay UE is to actas a relay. In addition, the timer can indicate a duration for which theeNodeB's authorization for the relay UE to act as a relay is valid. Therelay UE can operate in both idle mode and connected mode until expiryof the timer. In one example, the timer can be of a relatively longduration depending on the network configuration.

In one example, the sidelink maximum remote UE (SLmaxRemoteUEs)parameter can indicate a maximum number of remote UEs that can besupported by the relay UE. In Release 12, a relay UE can receive up to16 sidelink processes, which implies that the relay UE is capable ofsupporting up to 16 remote UEs simultaneously. In some cases, the eNodeBcan impose the relay UE to support fewer remote UEs depending oncongestion and/or interference levels.

In one example, the sidelink relay resource configuration(SLrelayResourceConfiguration) parameter can indicate specific poolconfiguration information that the relay UE can use to communicate tothe remote UE, which can potentially result in power savings. Forexample, this parameter can provide specific detailed resourceconfigurations for the relay UE, and the relay UE may share thisinformation with the remote UE or the in-coverage remote UE may alsoobtain this configuration via broadcast system information. Thisresource configuration may be used for an announcement of sidelinkdiscovery in a same cell or inter-frequency cells.

In one example, the sidelink remote UE authorization(SLremoteUEAuthorization) parameter can provide authorization for theremote UE. If this parameter is set to “ON,” then the relay UE does nothave to forward a remote UE identifier (ID) to the eNodeB over a newsidelink message or an existing sidelink message. As such the eNodeBdoes not have to explicitly authorize the remote UE. In this case, theauthentication between the remote UE and the relay UE, as well as aservice level authorization for the remote UE, are sufficient.

In one example, the sidelink relay control configuration(SLrelayControlConfiguration) parameter can indicate the relay UE torelease or redirect a remote UE. This can be applicable during anout-of-coverage to an in-coverage scenario. Based on this parameter, theeNodeB can provide control to the relay UE to be able to release ordirect remote UEs, such that the eNodeB is not involved in the releaseor direction of the remote UEs. However, in some cases, the eNodeB maywant to be involved for tighter control of the operation of remote UEtransitions.

As previously described, after the eNodeB communicates the relayinitiation and configuration message with the parameters to the relay UE(e.g., as part of an existing RRC message), the relay UE can beconfigured to act as a relay for the remote UE. In other words, therelay UE can utilize the parameters to act as a relay for the remote UE.The relay initiation and configuration message can be a dedicatedmessage that is communicated explicitly to the relay UE (i.e., notbroadcast).

In some cases, a given UE may not wish to be configured as a relay UE.For example, a given UE with a battery level that is below a definedthreshold may wish to not act as a relay, even though the UE isauthorized to act as a relay at a service level. In this case, the UEmay not initiate a relay operation on its own. In other words, the UEmay not communicate a sidelink UE information message to the eNodeBindicating an interest in acting as a relay. When the network initiatesthe UE to act as a relay (i.e., the UE does not express an interest toact as a relay), the UE which cannot comply with the new configurationspecified in the RRC connection reconfiguration message may continueusing a previous configuration, as per the current specification.

In one configuration, a remote UE can switch from having a connectionwith an eNodeB to having a connection with a relay UE. For example, theremote UE can initially be connected to an eNodeB over a Uu interface.In other words, the remote UE can be in-coverage of the eNodeB. Duringthis time, the remote UE can monitor a connection link quality (i.e., alink quality of the Uu interface) according to a legacy behavior. If theconnection link quality (or serving channel quality) becomes less than adefined threshold, but the remote UE does not detect any neighboringcells for handover, the remote UE can perform a discovery procedure forrelay UE selection. In other words, the remote UE can being searchingfor a relay UE. The discovery procedure can utilize Model A or Model B,as further described in 3GPP LTE Release 12. Once the remote UEdiscovers a relay UE in proximity to the remote UE, the remote UE canselect the relay UE based on the link quality.

In some cases, when the remote UE is in-coverage and directly connectedwith the eNodeB, the remote UE may wish to be released from the directconnection with the eNodeB (i.e., the Uu connection) upon establishingthe communication with the relay UE. After some time, the remote UE maybecome out-of-coverage of the eNodeB. These cases are further describedin FIGS. 13 and 14.

FIG. 13 illustrates exemplary signaling that enables a relay userequipment (UE) 1320 to act as a relay between an eNodeB 1330 and aremote UE 1310. The eNodeB 1330 can broadcast a relay configurationinformation message to the relay UE 1320. The relay configurationinformation message can be included in a system information block (SIB)18, a SIB 19 or another SIB. The relay UE 1320 and the remote UE 1310can perform a discovery procedure. The relay UE 1320 can initiate thediscovery procedure after determining to act as a relay based on therelay configuration information message received from the eNodeB 1330.Afterwards, the remote UE 1310 can communicate a direct communicationrequest to the relay UE 1320, and the relay UE 1320 and the remote UE1310 can perform a mutual authentication procedure. At this point, theremote UE 1310 and the relay UE 1320 may perform D2D communications witheach other.

In one example, the remote UE 1310 can transmit a newly defined messageor an existing message (e.g., a sidelink UE information message) to theeNodeB 1330 to inform the eNodeB 1330 that the remote UE 1310 hasestablished a relay-based connection with the relay UE 1320. The remoteUE 1310 can transmit the sidelink UE information message since theremote UE 1310 is still in-coverage of the eNodeB 1330. In addition, thesidelink UE information message can indicate the remote UE's desire tobe released from direct communications with the eNodeB 1330. Therefore,the connection between the remote UE 1310 and the eNodeB 1320 (i.e., theUu connection) can be released, and the remote UE 1310 may only beconnected with the relay UE 1320. Therefore, in this configuration, therelease of the Uu connection can be initiated by the remote UE 1310.

FIG. 14 illustrates exemplary signaling that enables a relay userequipment (UE) 1420 to act as a relay between an eNodeB 1430 and aremote UE 1410. The eNodeB 1430 can broadcast a relay configurationinformation message to the relay UE 1420. The relay configurationinformation message can be included in a system information block (SIB)18, a SIB 19 or another SIB. The relay UE 1420 and the remote UE 1410can perform a discovery procedure. The relay UE 1420 can initiate thediscovery procedure after determining to act as a relay based on therelay configuration information message received from the eNodeB 1430.Afterwards, the remote UE 1410 can communicate a direct communicationrequest to the relay UE 1420, and the relay UE 1420 and the remote UE1410 can perform a mutual authentication procedure. At this point, theremote UE 1410 and the relay UE 1420 may perform D2D communications witheach other.

In one example, after establishing a connection with the remote UE 1410,the relay UE 1420 can communicate a newly defined dedicated sidelinkmessage or an existing sidelink UE information message to the eNodeB1430, wherein this message may include information about the relay UE'sconnections to remote UEs. In particular, this message can includespecific identifiers (IDs) of remote UEs that are connected to the relayUE 1420. Based on this information, the eNodeB 1430 can perform an RRCconnection release with the remote UE 1410. In other words, the eNodeB1430 can release a Uu connection with the remote UE 1410. Therefore, inthis configuration, the release of the Uu connection can be initiated bythe relay UE 1420 and/or the eNodeB 1430, as opposed to the remote UE1410.

In one configuration, a remote UE can move from out-of-coverage toin-coverage of an eNodeB. The remote UE can establish a directconnection with the eNodeB using legacy procedures. In other words,after the remote UE is in a suitable cell, the remote UE can perform anRRC connection establishment procedure in order to establish a directconnection with the eNodeB. The remote UE may have been connected to arelay UE when out-of-coverage. In some cases, after establishing thedirect connection with the eNodeB, the remote UE may terminate theconnection with the relay UE (i.e., stop the UE-to-NW relayfunctionality). For example, the remote UE may discontinue using therelay UE as a relay after the remote UE detects any cell fulfilling theS criterion, as defined in 3GPP TS 36.304 Section 5.2.3.2. In anotherexample, the remote UE may discontinue using the relay UE as a relayafter the remote UE finds a suitable cell or a cell in a limitedservice. In yet another example, the remote UE may discontinue using therelay UE as a relay after the remote UE successfully establishes an RRCconnection, sends an RRC connection request, or establishes an EPSbearer for an application that was previously served by the relay UE.

In one example, the relay UE can redirect the remote UE to establish adirect Uu connection with the eNodeB, as the relay UE has access to boththe PC5 interface (i.e., the interface between the relay UE and theremote UE) and Uu link quality measurements (i.e., link qualitymeasurements between the relay UE and the eNodeB). In this case, if therelay UE determines that the PC5 link quality is above a certain upperthreshold, then the relay UE can recommend or initiate the remote UE toperform cell detection/measurements for establishing a direct linkconnection with the eNodeB. Once the remote UE has establishedcommunication with the eNodeB, the remote UE can request the relay UE tobe released on the relay link for a graceful transition.

In one configuration, the remote UE can initiate relay discovery andselection. In other words, an in-coverage ProSe enabled UE can initiatea relay discovery procedure. In a first scenario, the eNodeB can receivea measurement report (e.g., a report with RSRP and/or RSRQ measurements)from the remote UE, and if the measurement report indicates that a Uulink quality is below a certain threshold, the eNodeB can trigger adiscovery procedure in the remote UE. In a second scenario, the remoteUE can trigger a relay discovery procedure on its own based onadvertised thresholds in dedicated signaling or system information.

In one example, these thresholds can be set to conservative valuescompared to the S-criteria thresholds defined for the legacy cellselection procedure in LTE, as the remote UE will continue to maintainthe Uu connection until a relay communication is determined andestablished. The remote UE can support simultaneous operation on the PC5interface with the relay UE and the Uu connection with the eNodeB.

As previously described, the remote UE can trigger the relay discoveryprocedure on its own based on the advertised thresholds in dedicatedsignaling or system information. In one example, these thresholds can becommunicated to the remote UE via a sidelink discovery configurationinformation element (IE). The sidelink discovery configuration IE can becommunicated from the eNodeB to the remote UE in a SIB 18, a SIB 19, oran RRC connection reconfiguration message. Based on the thresholdsincluded in the sidelink discovery configuration IE, the remote UE caninitiate a discovery procedure to identify a relay UE that is located inproximity to the remote UE. In another example, these thresholds can beprovided where S-criteria thresholds are provided within the systeminformation message (e.g., SIB3), which is the trigger to an intra/intercell search.

FIGS. 15 and 16 are exemplary abstract syntax notation (ASN) codesdescribing a sidelink discovery configuration information element (IE).The sidelink discovery configuration IE (IE SL-DiscConfig) can becommunicated from the eNodeB to a remote UE. More specifically, thesidelink discovery configuration IE can be communicated via a SIB 18, aSIB 19, or an RRC connection reconfiguration or sidelink UE informationmessage. The sidelink discovery configuration IE can include variousmeasurement thresholds, which can be used by the remote UE to perform arelay discovery procedure. For example, the remote UE can compare itsown measurements (e.g., RSRP or RSRQ measurements) to the measurementthreshold, and based on the comparison, the remote UE can perform therelay discovery procedure and further relay communication. In otherwords, if a link quality between the remote UE and an eNodeB is lessthan a defined threshold, the remote UE can initiate the relay discoveryprocedure in order to identify a given UE to act as a relay between theeNodeB and the remote UE. The relaySelectionInfo parameters may also beinterpreted as cell selection information broadcast by a serving cell inSIB19 to be used by the remote UE to select a cell on another frequency.

In one example, the configuration information described above can beprovided from the eNodeB to the remote UE using another type ofdedicated signaling message while the remote UE is still in coverage ofthe eNodeB.

In one configuration, an out-of-coverage remote UE (or ProSe enabled UE)can initiate relay discovery and selection. In this scenario, thetechnique used by the out-of-coverage remote UE can be up to UEimplementation.

In one configuration, the relay UE may be associated with a particularRRC state during the discovery phase and the one-to-one communicationphase. During the discovery phase, the relay UE may not have anyon-going data activity in both the PC5 interface and the Uu interface.In the discovery phase, the relay UE is allowed to perform discovery (ifthe announcement of the discovery message is based on Model A) even whenthe relay UE is in RRC idle mode. The relay UE can initiate an RRCconnection establishment if the eNodeB requires the relay UE to obtaineNodeB authorization for discovery due to relay operations. Similar tothe discovery procedure in Release 12, if the eNodeB allocates discoveryresource via dedicated signaling, the UE should be in a connected modein order to receive the discovery resource configuration. If Model B ofthe discovery procedure is used, the relay UE should monitor only forthe discovery message. In this case, the relay UE can be kept in theidle mode. During the one-to-one communication phase, in order to routedata to the network, the relay UE should be in connected mode.

In one configuration, a relay reselection signaling optimization can beimplemented. In Release 12, the eNodeB, upon receiving a connectionestablishment request from a ProSe-enabled UE (i.e., a remote UE), hasto fetch ProSe UE context from the core network. For example, the eNodeBcan fetch the ProSe UE context from the core network via a mobilitymanagement entity (MME), a home subscriber server (HSS) and/or a ProSeFunction. In Release 13, if the remote UE uses a relay UE forcommunication and is to be authorized by the eNodeB for every relayreselection within the same eNodeB coverage, this may lead to anincreased amount of signaling overhead and latency.

In one example, if the eNodeB authorization is expected for the remoteUE which is out-of-coverage, then the relay UE can forward the remote UEID to the eNodeB. The remote UE ID can be an International MobileSubscriber Identity (IMSI), a ProSe UE ID, or a link layer ID. After therelay UE forwards the remote UE to the eNodeB, the eNodeB can fetch theProSe UE context from the core network. Then, the eNodeB can store thisProSe UE context (specifically for remote UEs) for a defined period oftime, such that the ProSe UE context can be re-utilized upon relayreselection.

FIG. 17 illustrates exemplary relay reselection signaling. Morespecifically, a relay selection procedure can be performed in which theeNodeB 1730 retrieves ProSe UE context from a core network (CN). TheProSe UE context can be associated with a remote UE 1710. The retrievalof the ProSe UE context can involve multiple nodes in the CN, such as amobility management entity (MME) 1740, a home subscriber server (HSS)1750, and a ProSe Function 1760.

In one example, an initial E-UTRAN attach and/or UE requested packetdata network (PDN) connectivity can be performed. The remote UE 1710 canperform a relay discovery procedure with a relay UE 1720, wherein therelay discovery procedure is in accordance with either Model A or ModelB. The remote UE 1710 can communicate a direct communication requestmessage to the relay UE 1720. The relay UE 1720 can communicate an RRCmessage (e.g., a sidelink UE information message) to the eNodeB 1730,wherein the RRC message includes a remote UE ID. The eNodeB 1730 canperform a ProSe authorization process for the remote UE 1710 based on asubscription. During this process, the eNodeB 1730 can retrieve remoteUE context information from the core network (i.e., the MME 1740, theHSS 1750 and the ProSe Function 1760). The eNodeB 1730 can communicatean RRC message response to the relay UE 1720, wherein the RRC messageresponse includes the remote UE ID. In addition, the relay UE 1720 cancommunicate a direct communication response message to the remote UE1710.

FIG. 18 illustrates exemplary relay reselection signaling. Morespecifically, a relay selection procedure can be performed in which theeNodeB 1830 retrieves stored ProSe UE context. The ProSe UE context canbe associated with a remote UE 1810. In this configuration, the eNodeB1830 does not have to retrieve the ProSe UE context from a core network(CN), wherein the CN includes a mobility management entity (MME) 1840, ahome subscriber server (HSS) 1850, and a ProSe Function 1860.

In one example, an initial E-UTRAN attach and/or UE requested packetdata network (PDN) connectivity can be performed. The remote UE 1810 canperform a relay discovery procedure with a relay UE 1820, wherein therelay discovery procedure is in accordance with either Model A or ModelB. The remote UE 1810 can communicate a direct communication requestmessage to the relay UE 1820. The relay UE 1820 can communicate an RRCmessage (e.g., a sidelink UE information message) to the eNodeB 1830,wherein the RRC message includes a remote UE ID. In this configuration,the eNodeB 1830 does not perform a ProSe authorization process for theremote UE 1810 based on a subscription. Rather, since remote UE contextinformation is already stored at the eNodeB 1830, the eNodeB 1830 cancommunicate an RRC message response to the relay UE 1820, wherein theRRC message response includes the remote UE ID. In addition, the relayUE 1820 can communicate a direct communication response message to theremote UE 1810.

As previously described, a relay UE can act as a relay between a remoteUE and an eNodeB when the remote UE is not connected to the eNodeB. Inone configuration, the remote UE can be associated with the followingfeatures: (1) The remote UE can be ProSe-enabled and capable ofcommunicating with the eNodeB via a direct communication or via therelay UE (also referred to as a UE-to-Network Relay). (2) The remote UEcan directly communicate a sidelink UE information message or a newlydefined message to the eNodeB in order to inform the eNodeB that theremote UE has identified a relay UE for communication, and therefore,the remote UE wishes to be released from direct communication with theeNodeB. (3) The remote UE can stop using the relay UE for communicationif the remote UE: detects a cell fulfilling the S-criterion, detects asuitable cell, or establishes a connection with the eNodeB. (4) Theremote UE can receive a command from the relay UE to switch to a directconnection with the relay UE. (5) The remote UE can trigger a relaydiscovery procedure based on a command from the eNodeB. (6) The remoteUE can trigger the relay discovery procedure by itself using broadcastlink quality thresholds and its own measurements. (7) The remote UE canreceive the link quality thresholds and relay initiation commands viasystem information or dedicated signaling.

In one configuration, the relay UE can be associated with the followingfeatures: (1) The relay UE can support ProSe D2D communication alongwith relay operation acting as a UE-to-Network relay to send or receivecommunication from the eNodeB on one side and other remote UEs from theother side. (2) The relay UE can receive a broadcast of certain relayconfiguration related parameters. The broadcast can be in existing ornew system information. These parameters can include thresholdparameters representing a link quality measurement between the relay UEand the remote UE, a mobility state parameter that should be satisfiedby the relay UE, and a parameter indicating whether the relay UEsupports acting as a relay from idle or connected mode. (3) The relay UEcan send a dedicated sidelink UE relay interest indication message tothe eNodeB. (4) The relay UE can receive a relay initiation andconfiguration within a ‘sl-RelayConfig-r13’ field. The relay initiationand configuration can be included in an RRC connection reconfigurationmessage, a new unicast or broadcast, or an existing or new systeminformation message received from the eNodeB.

Moreover, (5) The relay UE can process and apply the followingconfiguration parameters: SLrelayDiscoveryStart (to start the discoveryprocedure for the relay UE), t_relayDiscoveryPeriodicity (to specify thefrequency of relay advertisements), t_relayOperationTimer (validity ofthe relaying operation), SLmaxRemoteUEs (number of UEs that can beconnected through the relay UE), SLrelayResourceConfiguration (specificpool configuration information), SLremoteUEAuthorization (whether theremote UE may be authorized by the relay UE itself), andSLrelayControlConfiguration (whether the relay UE may release/redirectthe remote UEs by itself). (6) The relay UE can decide to act as a relaybased on internal information, such as serving cell measurements (incomparison to provided thresholds), battery status information, and userinput information. (7) The relay UE can decide to act as a relay uponreception of the configuration parameters from the eNodeB.

Moreover, (8) The relay UE can process a communication request messagefrom the remote UE, and initiate the relay process if not alreadyconfigured by the eNodeB using an existing message (e.g.,SidelinkUEinformation) or a newly defined message. (9) The relay UE cansend remote UE information (e.g. a remote UE ID) in a newly definedmessage or an existing message once the remote UE connection isestablished. (10) The relay UE can recommend a remote UE to switch itsconnection from relaying to direct communication based on PC5 and Uulink quality measurements and thresholds. (11) The relay UE candetermine if eNodeB authorization is required and initiate an RRCconnection establishment procedure before performing a relay discoveryprocess. (12) The remote UE can receive remote UE information (e.g.,eNodeB authorization, context information) in a newly defined message oran existing message in order to complete a remote UE one-to-oneconnection.

In one configuration, the eNodeB can be associated with the followingfeatures: (1) The eNodeB (or a similar network node) can support ProSeD2D groupcast and unicast communication along with relay operation. TheeNodeB can configure certain UEs to act as UE-to-Network relays and sendor receive communications from such relays. (2) The eNodeB can broadcastcertain relay configuration related parameters. The broadcast can be inexisting or new system information. These parameters can includethreshold parameters that represent link quality measurements betweenthe relay UE and the eNodeB, a mobility state parameter that should besatisfied by the relay UE, and a parameter indicating whether the relayUE supports acting as a relay from idle or connected mode. (3) TheeNodeB can receive a sidelink UE information (SidelinkUEInformation)message with a given UE's interest indication to act as a relay. (4) TheeNodeB can receive a dedicated sidelink UE relay interest indication(SideLinkUERelayInterestIndication) message from the relay UE. (5) TheeNodeB can send a relay initiation and configuration within a‘sl-RelayConfig-r13’ field. The relay initiation and configuration canbe included in an RRC connection reconfiguration message, a new unicastor broadcast, or an existing or new system information message receivedfrom the eNodeB.

Moreover, (6) The configuration parameters can include the following:SLrelayDiscovery Start (to start the discovery procedure for the relayUE), t_relayDiscoveryPeriodicity (to specify the frequency of relayadvertisements), t_relayOperationTimer (validity of the relayingoperation), SLmaxRemoteUEs (number of UEs that can be connected throughthe relay UE), SLrelayResourceConfiguration (specific pool configurationinformation), SLremoteUEAuthorization (whether the remote UE may beauthorized by the relay UE itself), and SLrelayControlConfiguration(whether the relay UE may release/redirect the remote UEs by itself).

Moreover, (7) The eNodeB can receive remote UE information (e.g., aremote UE ID) through the relay UE in a newly defined message or anexisting message once the remote UE connection is established throughthe relay UE, thereby releasing the remote UE's direct connection. (8)The eNodeB can send a message to the remote UE to initiate its relaydiscovery procedure based on the remote UE's measurement report. (9) TheeNodeB can send configuration information related to thresholds of linkquality measurements within a discovery configuration container or a newcontainer in a dedicated signaling message to the remote UE. (10) TheeNodeB can send configuration information to control the initiation ofthe relay discovery procedure of the remote UE. (11) The eNodeB canstore remote UE context upon fetching the remote UE context from thecore network for relay reselection purposes.

Another example provides functionality 1900 of a relay user equipment(UE) operable to act as a relay between a remote UE and an eNodeB, asshown in the flow chart in FIG. 19. The functionality can be implementedas a method or the functionality can be executed as instructions on amachine, where the instructions are included on at least one computerreadable medium or one non-transitory machine readable storage medium.The relay UE can comprise one or more processors and memory configuredto: receive, from the eNodeB, a relay configuration message thatincludes one or more relay configuration parameters, as in block 1910.The relay UE can comprise one or more processors and memory configuredto: identify relay UE information associated with one or more relayparameters of the relay UE, as in block 1920. The relay UE can compriseone or more processors and memory configured to: determine, at the relayUE, to act as the relay for the remote UE based on the one or more relayconfiguration parameters and the relay UE information, as in block 1930.The relay UE can comprise one or more processors and memory configuredto: transmit, from the relay UE, a discovery message to the remote UE inorder to establish a direct connection between the relay UE and theremote UE, wherein the relay UE is configured to relay data from theeNodeB to the remote UE via the direct connection between the relay UEand the remote UE, as in block 1940.

Another example provides functionality 2000 of a relay user equipment(UE) operable to act as a relay between a remote UE and an eNodeB, asshown in the flow chart in FIG. 20. The functionality can be implementedas a method or the functionality can be executed as instructions on amachine, where the instructions are included on at least one computerreadable medium or one non-transitory machine readable storage medium.The relay UE can comprise one or more processors and memory configuredto: receive, from the eNodeB, a relay configuration message thatincludes one or more relay configuration parameters, as in block 2010.The relay UE can comprise one or more processors and memory configuredto: determine, at the relay UE, that the relay UE is functional to actas the relay for the remote UE based on the one or more relayconfiguration parameters and relay UE information, as in block 2020. Therelay UE can comprise one or more processors and memory configured to:transmit, from the relay UE, a sidelink information message to theeNodeB to indicate that the relay UE is functional to act as the relayfor the remote UE, as in block 2030. The relay UE can comprise one ormore processors and memory configured to: receive, from the eNodeB, arelay initiation and configuration message that authorizes the relay UEto act as the relay for the remote UE, as in block 2040.

Another example provides at least one machine readable storage mediumhaving instructions 2100 embodied thereon for instructing a relay userequipment (UE) to act as a relay between an eNodeB and a remote UE, asshown in the flow chart in FIG. 21. The method can be executed asinstructions on a machine, where the instructions are included on atleast one computer readable medium or one non-transitory machinereadable storage medium. The instructions when executed perform thefollowing: transmitting, using at least one processor of the eNodeB, arelay configuration message to the relay UE that includes one or morerelay configuration parameters, as in block 2110. The instructions whenexecuted perform the following: receiving, using the at least oneprocessor of the eNodeB, a sidelink information message from the relayUE that indicates the relay UE is functional to act as the relay for theremote UE, wherein the relay UE is configured to determine that therelay UE is functional to act as the relay based on the one or morerelay configuration parameters and relay UE information, as in block2120. The instructions when executed perform the following:transmitting, using the at least one processor of the eNodeB, a relayinitiation and configuration message to the relay UE that authorizes therelay UE to act as the relay for the remote UE, wherein the relay UE isconfigured to establish a direct connection between the relay UE and theremote UE based on the relay initiation and configuration messagereceived from the eNodeB, as in block 2130.

Another example provides functionality 2200 of a remote user equipment(UE) operable to communicate with an eNodeB via a relay UE, as shown inthe flow chart in FIG. 22. The functionality can be implemented as amethod or the functionality can be executed as instructions on amachine, where the instructions are included on at least one computerreadable medium or one non-transitory machine readable storage medium.The remote UE can comprise one or more processors and memory configuredto: establish, at the remote UE, a direct connection with the relay UEvia a discovery procedure, wherein the remote UE is configured toestablish the direct connection with the relay UE using one or morerelay configuration parameters received from the eNodeB in broadcast ordedicated signaling, as in block 2210. The remote UE can comprise one ormore processors and memory configured to: communicate, to the eNodeB, asidelink information message that indicates the remote UE hasestablished the direct connection with the relay UE and requests for theeNodeB to release a radio resource control (RRC) connection with theremote UE, wherein the eNodeB is configured to release the RRCconnection with the remote UE, as in block 2220.

FIG. 23 provides an example illustration of a user equipment (UE) device2300, such as a wireless device, a mobile station (MS), a mobilewireless device, a mobile communication device, a tablet, a handset, orother type of wireless device. The UE device 2300 can include one ormore antennas configured to communicate with a node or transmissionstation, such as a base station (BS), an evolved Node B (eNB), abaseband unit (BBU), a remote radio head (RRH), a remote radio equipment(RRE), a relay station (RS), a radio equipment (RE), a remote radio unit(RRU), a central processing module (CPM), or other type of wireless widearea network (WWAN) access point. The UE device 2300 can be configuredto communicate using at least one wireless communication standardincluding 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth,and WiFi. The UE device 2300 can communicate using separate antennas foreach wireless communication standard or shared antennas for multiplewireless communication standards. The UE device 2300 can communicate ina wireless local area network (WLAN), a wireless personal area network(WPAN), and/or a WWAN.

In some embodiments, the UE device 2300 may include applicationcircuitry 2302, baseband circuitry 2304, Radio Frequency (RF) circuitry2306, front-end module (FEM) circuitry 2308 and one or more antennas2310, coupled together at least as shown.

The application circuitry 2302 may include one or more applicationprocessors. For example, the application circuitry 2302 may includecircuitry such as, but not limited to, one or more single-core ormulti-core processors. The processor(s) may include any combination ofgeneral-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the system.

The baseband circuitry 2304 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 2304 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 2306 and to generate baseband signalsfor a transmit signal path of the RF circuitry 2306. Baseband processingcircuitry 2304 may interface with the application circuitry 2302 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 2306. For example, in some embodiments,the baseband circuitry 2304 may include a second generation (2G)baseband processor 2304 a, third generation (3G) baseband processor 2304b, fourth generation (4G) baseband processor 2304 c, and/or otherbaseband processor(s) 2304 d for other existing generations, generationsin development or to be developed in the future (e.g., fifth generation(5G), 6G etc.). The baseband circuitry 2304 (e.g., one or more ofbaseband processors 2304 a-d) may handle various radio control functionsthat enable communication with one or more radio networks via the RFcircuitry 2306. The radio control functions may include, but are notlimited to, signal modulation/demodulation, encoding/decoding, radiofrequency shifting, etc. In some embodiments, modulation/demodulationcircuitry of the baseband circuitry 2304 may include Fast-FourierTransform (FFT), precoding, and/or constellation mapping/demappingfunctionality. In some embodiments, encoding/decoding circuitry of thebaseband circuitry 2304 may include convolution, tail-bitingconvolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC)encoder/decoder functionality. Embodiments of modulation/demodulationand encoder/decoder functionality are not limited to these examples andmay include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry 2304 may include elements ofa protocol stack such as, for example, elements of an evolved universalterrestrial radio access network (EUTRAN) protocol including, forexample, physical (PHY), media access control (MAC), radio link control(RLC), packet data convergence protocol (PDCP), and/or radio resourcecontrol (RRC) elements. A central processing unit (CPU) 2304 e of thebaseband circuitry 2304 may be configured to run elements of theprotocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRClayers. In some embodiments, the baseband circuitry may include one ormore audio digital signal processor(s) (DSP) 2304 f The audio DSP(s) 104f may be include elements for compression/decompression and echocancellation and may include other suitable processing elements in otherembodiments. Components of the baseband circuitry may be suitablycombined in a single chip, a single chipset, or disposed on a samecircuit board in some embodiments. In some embodiments, some or all ofthe constituent components of the baseband circuitry 2304 and theapplication circuitry 2302 may be implemented together such as, forexample, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 2304 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 2304 may supportcommunication with an evolved universal terrestrial radio access network(EUTRAN) and/or other wireless metropolitan area networks (WMAN), awireless local area network (WLAN), a wireless personal area network(WPAN). Embodiments in which the baseband circuitry 2304 is configuredto support radio communications of more than one wireless protocol maybe referred to as multi-mode baseband circuitry.

The RF circuitry 2306 may enable communication with wireless networksusing modulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 2306 may include switches,filters, amplifiers, etc. to facilitate the communication with thewireless network. RF circuitry 2306 may include a receive signal pathwhich may include circuitry to down-convert RF signals received from theFEM circuitry 2308 and provide baseband signals to the basebandcircuitry 2304. RF circuitry 2306 may also include a transmit signalpath which may include circuitry to up-convert baseband signals providedby the baseband circuitry 2304 and provide RF output signals to the FEMcircuitry 2308 for transmission.

In some embodiments, the RF circuitry 2306 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 2306 may include mixer circuitry 2306 a, amplifier circuitry2306 b and filter circuitry 2306 c. The transmit signal path of the RFcircuitry 2306 may include filter circuitry 2306 c and mixer circuitry2306 a. RF circuitry 2306 may also include synthesizer circuitry 2306 dfor synthesizing a frequency for use by the mixer circuitry 2306 a ofthe receive signal path and the transmit signal path. In someembodiments, the mixer circuitry 2306 a of the receive signal path maybe configured to down-convert RF signals received from the FEM circuitry2308 based on the synthesized frequency provided by synthesizercircuitry 2306 d. The amplifier circuitry 2306 b may be configured toamplify the down-converted signals and the filter circuitry 2306 c maybe a low-pass filter (LPF) or band-pass filter (BPF) configured toremove unwanted signals from the down-converted signals to generateoutput baseband signals. Output baseband signals may be provided to thebaseband circuitry 2304 for further processing. In some embodiments, theoutput baseband signals may be zero-frequency baseband signals, althoughthis is not a requirement. In some embodiments, mixer circuitry 2306 aof the receive signal path may comprise passive mixers, although thescope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 2306 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 2306 d togenerate RF output signals for the FEM circuitry 2308. The basebandsignals may be provided by the baseband circuitry 2304 and may befiltered by filter circuitry 2306 c. The filter circuitry 2306 c mayinclude a low-pass filter (LPF), although the scope of the embodimentsis not limited in this respect.

In some embodiments, the mixer circuitry 2306 a of the receive signalpath and the mixer circuitry 2306 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedown-conversion and/or up-conversion respectively. In some embodiments,the mixer circuitry 2306 a of the receive signal path and the mixercircuitry 2306 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 2306 a of thereceive signal path and the mixer circuitry 2306 a may be arranged fordirect down-conversion and/or direct up-conversion, respectively. Insome embodiments, the mixer circuitry 2306 a of the receive signal pathand the mixer circuitry 2306 a of the transmit signal path may beconfigured for super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 2306 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry2304 may include a digital baseband interface to communicate with the RFcircuitry 2306.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 2306 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 2306 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider.

The synthesizer circuitry 2306 d may be configured to synthesize anoutput frequency for use by the mixer circuitry 2306 a of the RFcircuitry 2306 based on a frequency input and a divider control input.In some embodiments, the synthesizer circuitry 2306 d may be afractional N/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 2304 orthe applications processor 2302 depending on the desired outputfrequency. In some embodiments, a divider control input (e.g., N) may bedetermined from a look-up table based on a channel indicated by theapplications processor 2302.

Synthesizer circuitry 2306 d of the RF circuitry 2306 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 2306 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (fLO). In someembodiments, the RF circuitry 2306 may include an IQ/polar converter.

FEM circuitry 2308 may include a receive signal path which may includecircuitry configured to operate on RF signals received from one or moreantennas 2310, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 2306 for furtherprocessing. FEM circuitry 2308 may also include a transmit signal pathwhich may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 2306 for transmission by oneor more of the one or more antennas 2310.

In some embodiments, the FEM circuitry 2308 may include a TX/RX switchto switch between transmit mode and receive mode operation. The FEMcircuitry may include a receive signal path and a transmit signal path.The receive signal path of the FEM circuitry may include a low-noiseamplifier (LNA) to amplify received RF signals and provide the amplifiedreceived RF signals as an output (e.g., to the RF circuitry 2306). Thetransmit signal path of the FEM circuitry 2308 may include a poweramplifier (PA) to amplify input RF signals (e.g., provided by RFcircuitry 2306), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 2310.

FIG. 24 provides an example illustration of the wireless device, such asa user equipment (UE), a mobile station (MS), a mobile wireless device,a mobile communication device, a tablet, a handset, or other type ofwireless device. The wireless device can include one or more antennasconfigured to communicate with a node, macro node, low power node (LPN),or, transmission station, such as a base station (BS), an evolved Node B(eNB), a baseband processing unit (BBU), a remote radio head (RRH), aremote radio equipment (RRE), a relay station (RS), a radio equipment(RE), or other type of wireless wide area network (WWAN) access point.The wireless device can be configured to communicate using at least onewireless communication standard such as, but not limited to, 3GPP LTE,WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. Thewireless device can communicate using separate antennas for eachwireless communication standard or shared antennas for multiple wirelesscommunication standards. The wireless device can communicate in awireless local area network (WLAN), a wireless personal area network(WPAN), and/or a WWAN. The wireless device can also comprise a wirelessmodem. The wireless modem can comprise, for example, a wireless radiotransceiver and baseband circuitry (e.g., a baseband processor). Thewireless modem can, in one example, modulate signals that the wirelessdevice transmits via the one or more antennas and demodulate signalsthat the wireless device receives via the one or more antennas.

FIG. 24 also provides an illustration of a microphone and one or morespeakers that can be used for audio input and output from the wirelessdevice. The display screen can be a liquid crystal display (LCD) screen,or other type of display screen such as an organic light emitting diode(OLED) display. The display screen can be configured as a touch screen.The touch screen can use capacitive, resistive, or another type of touchscreen technology. An application processor and a graphics processor canbe coupled to internal memory to provide processing and displaycapabilities. A non-volatile memory port can also be used to providedata input/output options to a user. The non-volatile memory port canalso be used to expand the memory capabilities of the wireless device. Akeyboard can be integrated with the wireless device or wirelesslyconnected to the wireless device to provide additional user input. Avirtual keyboard can also be provided using the touch screen.

EXAMPLES

The following examples pertain to specific technology embodiments andpoint out specific features, elements, or actions that can be used orotherwise combined in achieving such embodiments.

Example 1 includes an apparatus of a relay user equipment (UE) operableto act as a relay between a remote UE and an eNodeB, the apparatuscomprising one or more processors and memory configured to: receive,from the eNodeB, a relay configuration message that includes one or morerelay configuration parameters; identify relay UE information associatedwith one or more relay parameters of the relay UE; determine, at therelay UE, to act as the relay for the remote UE based on the one or morerelay configuration parameters and the relay UE information; andtransmit, from the relay UE, a discovery message to the remote UE inorder to establish a direct connection between the relay UE and theremote UE, wherein the relay UE is configured to relay data from theeNodeB to the remote UE via the direct connection between the relay UEand the remote UE.

Example 2 includes the apparatus of Example 1, further configured totransmit a sidelink information message to the eNodeB to indicate thatthe relay UE is acting as the relay for the remote UE.

Example 3 includes the apparatus of any of Examples 1-2, wherein therelay UE is in coverage of the eNodeB and the remote UE isout-of-coverage with the eNodeB.

Example 4 includes the apparatus of any of Examples 1-3, wherein therelay UE is configured to receive the relay configuration message in adefined system information block (SIB) via a broadcast from the eNodeB.

Example 5 includes the apparatus of any of Examples 1-4, wherein therelay configuration parameters include one or more of: a first qualitythreshold parameter that represents a minimum link quality for the relayUE to act as the relay; a second quality threshold parameter thatrepresents a maximum link quality after which the relay UE cannot act asthe relay; a relay mobility configuration parameter that indicates anacceptable mobility state for the relay UE; an idle parameter thatindicates whether the relay UE is permitted to perform discovery andinitiate a relay operation from idle mode; and a relay operationsupported parameter that represents whether a cell associated with theeNodeB permits relay operation.

Example 6 includes the apparatus of any of Examples 1-5, wherein therelay UE information includes one or more of: a serving cellmeasurement, battery status information and user settings.

Example 7 includes the apparatus of any of Examples 1-6, wherein therelay UE is configured to determine to act as the relay based on acomparison between serving cell measurements included in the relay UEinformation and quality threshold parameters included in the one or moreconfiguration parameters.

Example 8 includes the apparatus of any of Examples 1-7, wherein therelay UE includes at least one of an antenna, a touch sensitive displayscreen, a speaker, a microphone, a graphics processor, an applicationprocessor, a baseband processor, an internal memory, a non-volatilememory port, and combinations thereof.

Example 9 includes an apparatus of a relay user equipment (UE) operableto act as a relay between a remote UE and an eNodeB, the apparatuscomprising one or more processors and memory configured to: receive,from the eNodeB, a relay configuration message that includes one or morerelay configuration parameters; determine, at the relay UE, that therelay UE is functional to act as the relay for the remote UE based onthe one or more relay configuration parameters and relay UE information;transmit, from the relay UE, a sidelink information message to theeNodeB to indicate that the relay UE is functional to act as the relayfor the remote UE; and receive, from the eNodeB in broadcast ordedicated signaling, a relay initiation and configuration parameter setthat authorizes the relay UE to act as the relay for the remote UE.

Example 10 includes the apparatus of Example 9, further configured totransmit, from the relay UE, a discovery message to the remote UE inorder to establish a direct connection between the relay UE and theremote UE, wherein the relay UE is configured to relay data from theeNodeB to the remote UE via the direct connection between the relay UEand the remote UE.

Example 11 includes the apparatus of any of Examples 9-10, wherein therelay UE is configured to: receive the relay configuration message in adefined system information block (SIB) via a broadcast from the eNodeB;and receive the relay initiation and configuration message via dedicatedsignaling from the eNodeB.

Example 12 includes the apparatus of any of Examples 9-11, wherein therelay initiation and configuration message includes one or more relayconfiguration parameters that are specific to the relay UE.

Example 13 includes the apparatus of any of Examples 9-12, wherein therelay UE is in coverage of the eNodeB and the remote UE isout-of-coverage with the eNodeB.

Example 14 includes the apparatus of any of Examples 9-13, wherein therelay UE information includes one or more of: a serving cellmeasurement, battery status information and user settings.

Example 15 includes the apparatus of any of Examples 9-14, wherein therelay UE is configured to determine that the relay UE is functional toact as the relay based on a comparison between serving cell measurementsincluded in the relay UE information and quality threshold parametersincluded in the one or more configuration parameters sent in broadcastsignaling from the eNB.

Example 16 includes at least one machine readable storage medium havinginstructions embodied thereon for instructing a relay user equipment(UE) to act as a relay between an eNodeB and a remote UE, theinstructions when executed perform the following: transmitting, using atleast one processor of the eNodeB, a relay configuration message to therelay UE that includes one or more relay configuration parameters;receiving, using the at least one processor of the eNodeB, a sidelinkinformation message from the relay UE that indicates the relay UE isfunctional to act as the relay for the remote UE, wherein the relay UEis configured to determine that the relay UE is functional to act as therelay based on the one or more relay configuration parameters and relayUE information; and transmitting, using the at least one processor ofthe eNodeB, a relay initiation and configuration message to the relay UEthat authorizes the relay UE to act as the relay for the remote UE,wherein the relay UE is configured to establish a direct connectionbetween the relay UE and the remote UE based on the relay initiation andconfiguration message received from the eNodeB.

Example 17 includes the at least one machine readable storage medium ofExample 16, further comprising instructions which when executed by theat least one processor of the eNodeB performs the following:transmitting data to the remote UE via the relay UE, wherein the relayUE is configured to receive the data from the eNodeB and relay the datato the remote UE via the direct connection between the relay UE and theremote UE.

Example 18 includes the at least one machine readable storage medium ofany of Examples 16-17, wherein the relay UE is in coverage of the eNodeBand the remote UE is out-of-coverage with the eNodeB or in coverage ofthe eNodeB.

Example 19 includes the at least one machine readable storage medium ofany of Examples 16-18, wherein eNodeB transmits the relay configurationparameters to the relay UE via a broadcast message and the eNodeBtransmits the relay initiation and configuration message to the relay UEvia dedicated signaling.

Example 20 includes the at least one machine readable storage medium ofany of Examples 16-19, further comprising instructions which whenexecuted by the at least one processor of the eNodeB performs thefollowing: transmitting the relay initiation and configuration messageto the relay UE to authorize the relay UE to act as the relay afterreceiving a measurement report from the remote UE when the remote UE isin coverage of the eNodeB, wherein the measurement report indicates thata connection between the remote UE and the eNodeB is below a definedthreshold

Example 21 includes the at least one machine readable storage medium ofany of Examples 16-20, further comprising instructions which whenexecuted by the at least one processor of the eNodeB performs thefollowing: receiving a message from the relay UE indicating that thedirect connection between the relay UE and the remote UE is successfullyestablished, wherein the remote UE is in coverage of the eNodeB; andreleasing a radio resource control (RRC) connection with the remote UE.

Example 22 includes an apparatus of a remote user equipment (UE)operable to communicate with an eNodeB via a relay UE, the apparatuscomprising one or more processors and memory configured to: establish,at the remote UE, a direct connection with the relay UE via a discoveryprocedure, wherein the remote UE is configured to establish the directconnection with the relay UE using one or more relay configurationparameters received from the eNodeB in broadcast or dedicated signaling;and communicate, to the eNodeB, a sidelink information message thatindicates the remote UE has established the direct connection with therelay UE and requests for the eNodeB to release a radio resource control(RRC) connection with the remote UE, wherein the eNodeB is configured torelease the RRC connection with the remote UE.

Example 23 includes the apparatus of Example 22, further configured toperform data communications with the eNodeB via the relay UE, whereinthe relay UE is configured to receive data from the eNodeB or the remoteUE and relay the data to the remote UE or the eNodeB, respectively, viathe direct connection between the relay UE and the remote UE.

Example 24 includes the apparatus of any of Examples 22-23, furtherconfigured to drop the direct connection with the relay UE after therelay UE becomes in coverage with a second eNodeB and establishes aconnection with the second eNodeB.

Example 25 includes the apparatus of any of Examples 22-24, furtherconfigured to establish the direct connection with the relay UE based onan instruction from the eNodeB, wherein the eNodeB sends the instructionafter receiving a measurement report from the remote UE that indicates aquality of the RRC connection between the remote UE and the eNodeB isbelow a defined threshold.

Example 26 includes the apparatus of any of Examples 22-25, furtherconfigured to trigger the discovery procedure for establishing thedirect connection with the relay UE when a quality of the Uu connectionbetween the remote UE and the eNodeB is below a defined threshold.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, compact disc-read-only memory (CD-ROMs), harddrives, non-transitory computer readable storage medium, or any othermachine-readable storage medium wherein, when the program code is loadedinto and executed by a machine, such as a computer, the machine becomesan apparatus for practicing the various techniques. A non-transitorycomputer readable storage medium can be a computer readable storagemedium that does not include signal. In the case of program codeexecution on programmable computers, the computing device may include aprocessor, a storage medium readable by the processor (includingvolatile and non-volatile memory and/or storage elements), at least oneinput device, and at least one output device. The volatile andnon-volatile memory and/or storage elements may be a random-accessmemory (RAM), erasable programmable read only memory (EPROM), flashdrive, optical drive, magnetic hard drive, solid state drive, or othermedium for storing electronic data. The node and wireless device mayalso include a transceiver module (i.e., transceiver), a counter module(i.e., counter), a processing module (i.e., processor), and/or a clockmodule (i.e., clock) or timer module (i.e., timer). One or more programsthat may implement or utilize the various techniques described hereinmay use an application programming interface (API), reusable controls,and the like. Such programs may be implemented in a high levelprocedural or object oriented programming language to communicate with acomputer system. However, the program(s) may be implemented in assemblyor machine language, if desired. In any case, the language may be acompiled or interpreted language, and combined with hardwareimplementations.

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group), and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablehardware components that provide the described functionality. In someembodiments, the circuitry may be implemented in, or functionsassociated with the circuitry may be implemented by, one or moresoftware or firmware modules. In some embodiments, circuitry may includelogic, at least partially operable in hardware.

It should be understood that many of the functional units described inthis specification have been labeled as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising customvery-large-scale integration (VLSI) circuits or gate arrays,off-the-shelf semiconductors such as logic chips, transistors, or otherdiscrete components. A module may also be implemented in programmablehardware devices such as field programmable gate arrays, programmablearray logic, programmable logic devices or the like.

Modules may also be implemented in software for execution by varioustypes of processors. An identified module of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions, which may, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedmodule may not be physically located together, but may comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the module and achieve the stated purposefor the module.

Indeed, a module of executable code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different storage devices, and may exist, atleast partially, merely as electronic signals on a system or network.The modules may be passive or active, including agents operable toperform desired functions.

Reference throughout this specification to “an example” or “exemplary”means that a particular feature, structure, or characteristic describedin connection with the example is included in at least one embodiment ofthe present technology. Thus, appearances of the phrases “in an example”or the word “exemplary” in various places throughout this specificationare not necessarily all referring to the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presenttechnology may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as defactoequivalents of one another, but are to be considered as separate andautonomous representations of the present technology.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of layouts, distances, network examples, etc., to provide athorough understanding of embodiments of the technology. One skilled inthe relevant art will recognize, however, that the technology can bepracticed without one or more of the specific details, or with othermethods, components, layouts, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the technology.

While the forgoing examples are illustrative of the principles of thepresent technology in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the technology. Accordingly, it is notintended that the technology be limited, except as by the claims setforth below.

What is claimed is:
 1. An apparatus of a relay user equipment (UE)operable to act as a relay between a remote UE and a base station, theapparatus comprising: memory; and one or more processors configured to:receive, from the base station, a relay configuration message thatincludes one or more relay configuration parameters; identify relay UEinformation associated with one or more relay parameters of the relayUE; determine, at the relay UE, to act as the relay for the remote UEbased on the one or more relay configuration parameters and the relay UEinformation, wherein the relay configuration parameters include a relaymobility configuration parameter that indicates an acceptable mobilitystate for the relay UE to act as the relay, a first quality thresholdparameter that represents a minimum link quality for the relay UE to actas the relay, and a second quality threshold parameter that represents amaximum link quality after which the relay UE cannot act as the relay;and transmit, from the relay UE, a discovery message to the remote UE inorder to establish a direct connection between the relay UE and theremote UE, wherein the relay UE is configured to relay data from thebase station to the remote UE via the direct connection between therelay UE and the remote UE.
 2. The apparatus of claim 1, furtherconfigured to transmit a sidelink information message to the basestation to indicate that the relay UE is acting as the relay for theremote UE.
 3. The apparatus of claim 1, wherein the relay UE is incoverage of the base station and the remote UE is out-of-coverage withthe base station.
 4. The apparatus of claim 1, wherein the relay UE isconfigured to receive the relay configuration message in a definedsystem information block (SIB) via a broadcast from the base station. 5.The apparatus of claim 1, wherein the relay configuration parametersfurther comprises: an idle parameter that indicates whether the relay UEis permitted to perform discovery and initiate a relay operation fromidle mode; and a relay operation supported parameter that representswhether a cell associated with the base station permits relay operation.6. The apparatus of claim 1, wherein the relay UE information includesone or more of: a serving cell measurement, battery status informationand user settings.
 7. The apparatus of claim 1, wherein the relay UE isconfigured to determine to act as the relay based on a comparisonbetween serving cell measurements included in the relay UE informationand quality threshold parameters included in the one or moreconfiguration parameters.
 8. The apparatus of claim 1, wherein the relayUE includes at least one of an antenna, a touch sensitive displayscreen, a speaker, a microphone, a graphics processor, an applicationprocessor, a baseband processor, an internal memory, a non-volatilememory port, and combinations thereof.